Electron-discharge device



Sept. 28 1926.

T. R. GRIFFITH ELECTRON DISCHARGE DEVICE Filed Oct. 5, 1920 2 Sheets-Sheet 1 Sept. 2B T926.

LGUUOGS T. R. GRIFFITH ELECTRON DISCHARGE DEVICE Filed oef. 5, 1920 2 sheets-sheet 2 I 79 il.' @EXW 2* Patented Sept. 28, 1926.

THOMAS R. GRIFFITH, OF DOVER, NEW JERSEY,

ASSIGrNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRON-DISCHARGE DEVICE.

Application filed` October 5, 1920. Serial No. 414,818.

voltages and capable of being readily and accurately made.

t Another object of the invention is to pro-V vide electron discharge devices, adapted to 'have their anodes cooled by contact with a suitable cooling medium, such as water or oil for example.

In the design of three element electron discharge devicesto be used at high voltages, the question ot insulation between elements becomes an important one. The socalled two-ended type of structure in which the anode as one unit is mounted on a stem sealedinto one end of the bulb and the grid and filament as another unit are mounted on a second stem sealed into the opposite end of the bulb, has given, in general. the required insulation. However, in making such a device the sealing in of one of the stems is also a line up process as the glass blower must align the two stems by eye while the last seal is Huid. This process is diiiicult and also results in considerable variation in impedance in different devices. The present invention provides a stem on which both electrode units may be mounted so that they may be aligned before sealing in, and yet the invention gives good high voltage protection as does the so called twoended tube. Thus, the necessity of aligning electrodes during sealing is avoided.

In the accompanying drawings Fig. 1 shows an electron discharge device embodying the invention. Fig. 2 shows the preterred form yof device made -in accordance with the invention, the anode being cooled by contact with a suitableiuid.

In Fig. 1 the electron discharge device 2 comprises envelope 3, the lower end 4 of which is drawnin asusual and is sealed at 6 to an electrodesupporting stem 7 which projects into the envelope. The stem 7 comprises an outer tubular portion Sand anA inner tubular portion 9. the Atop of the portion 8 being connected to the bottom of the top of the portion 10 is closed.

A metallic collar 12 is mounted on the portion 8 and carries metallic standards 13,

which support anode 14 shown as a cylinder.

disc,

' scoping the portions of vportion 9 by -a tubular portion 10. The

A metallic collar 16 is mounted on the portion 9 and carries metallic standards 17, which support. a grid 2O and a cathode 21. Intermediate their ends the standards 17 carry a metallic ring or band 22 within which a lavite disc 23 is secured by means of screws 24. At their upper ends, the standards 17 carry a'band or ring 26' within whicha lavite disc 27 is secured by 'Screws 28. Grid wires 30 are fastened to the portion ofthe standards 17 'between lavite discs 23 and 27. Wires 32 pass loosely through lavite disc 27 and are supported on springs 33 which rest on the disc 27. Wires 35 are fastened in the disc 23 and extend abovethe two of them' also extending below the disc. ,The cathode filament 21-is mounted on the wires 32 and 35. Leading-in wires 37 and 38 for the cathode are attached to the wires 35 which extend below disc 23, wires 37 and 38 passing through the closed end of the portion 9.. Leading-in wire 39 for the grid is attached to one of the standards 17 and -also passes through the closed end of tube 9. A leading-in wire 40 for the anode is sealed into the end of the vacuum tube opposite the stem 7. It is evident that in Fig. 1 the grid surrounds the cathode and the cylindrical anode surrounds the grid and the cathode.

The stem 7 is preferablyformed from a tube having two portions of .diii'erent diameters and a tapering connecting portion by heating the connecting portion and telediii'erent diameters, at the same time, reducing the air pressure in the tube to cause the connecting portion to lie close tothe portion of a larger diameter. For a given distance between collars 12 and 16, these collars are more thoroughly insulated from each other the wider 'the space between the tubular portions 9 and 10 in comparison to the space between the tubular portions 8 and 10, since in the finished vacuum tube the space between 9 and 10 is highly evacuated.

In Fig. 2 the `electron dischargedevice 45 comprises envelope 46 which has one end drawn inat 47 as usual and sealed at 48 to electrode supporting stem 49 which projects lcomprises two concentric tubular portions 51 and 52 :paced apart except at the central portion where they are sealed together as at 53. An anode 55, preferably of a metal such as platinum having a temperature coeliicient of expansion substantially the saine as that of glass, is sealed to the top of the tubular portion 51. The anode is shown in the forni of a dome forming a part ot the wall ot' the envelope. A metallic collar 57 is mounted on the upper parl oi' the tubular portion 52 and carries metallic standards 59 which support a grid Gt) and a cathode (S1, the cathode being shown as a looped filament. A lavite ring (33 is held between projections 64 on standards 59 and is lied to the standards by means of tie wires G5 passing through the ring and the projections. lVires G6 fastened in the ring 63 support the cathode filament 61. The lower ends of the loops of the filament engage wires (37 slidably mounted in the lavite ring 69. Projections on standards 59 prevent upward moyement of ring 69, and springs 71 bearing against ring 69 force the wires G7 downwardly. 'A wire 72 is belted about the standards 59 to hold them in engagement with the ring 69 and prevent them from spreading. The grid 60 comprises metallic rods 73 fixed in one ot the rings 63 and 69 and slidablc in the other of these rings, grid wires 75 being fastened to the rods 73. Leading-in wires 77 and 78 for the cathode are attached to two of the wires 66, and leading-in wire 79 for the grid is attached to the top of one ot the wires 78. A wire 81 Connected to the lower end of the anode and sealed through the tubular portion 51 near the lower cnd of said portion, Jforms the eX- ternal connection for the anode. It is evident that in Fig. 2 the grid surrounds the hollow anode and the cathode surrounds the grid and the anode. The lower end of the tubular portion 51 is closed by disc 83 through which pass two tubes 84 and 85, the tube S4 extending nearly to the upper end of the anode. A suitable cooling fluid such as water or oil may be passed into the tube S4 and out of the tube S5, for cooling the anode 55 and associated parts.

The stem 49 is preferably made by telescoping two tubes 51 and 52 and scaling them together intermediate their ends as at 53. The anodecarrying its leading-in wire 81, is then sealed on to one end ot the tubular portion 51.- The collar 57 carrying the grid and cathode is mounted on the upper part ot the tubular portion 52. The three electrodes are properly aligned with respect to cach other and the stem. Finally the stem is sealed to the envelope 47 as' at 48 and the leads 77, 7 Sand 79 are sealedthrough the upper end'of the envelope 47 .5

The insulation between the elements of clectron'-discharge devices is of importance not merely from the point of view of the lealageresistanee along the surface of the glass parts of the device, but also from the point of view of the length of, and the gas pressure in, gaps between elements at diticrent potentials, and troni the point of view of the dielectric hysteresis and the conduction of current in the insulation between the elements of dill'erent potentials. The collars 12 and 16 (Fig. 1) and 57 (Fig. 2) and the part of the anode 55 which is in contact with the glass part of the device are of large area, to reduce heating due to the dielectric hysteresis, for the heating of glass not unl lends to increase conduction current througli the glass, but also increases the dielectric. hysteresis loss in the glass.

'l" he particular feature of supporting electrodes from a collar on the stem of a vacuum tube is the invent-ion ot lVilliam F. Hendry and is claimed in his application Serial No. 217,565, tiled February 16, 1918 entitled- Vacuum tubes, assigned to the assignee ot this' application; the broad feature of supporting the electrodes from collars mounted on two concentric tubular portions on an inwardly projecting stein ot a vacuum tube is the invention of Robert lV. King and is claimed in his Patent No. 1,472,477, dated October` 30, 1923, entitled Electron discharge devices, assigned to the assignee of this application, and the broad feature of the reentrant anode forming a part of the envelope of the vacuum tube and adapted to be cooled by contact with a suitable cooling fluid is the invention of Howard W. lVeinhart, Patent No. 1,482,931, dated October 24, 1922, entitled Electron discharge devicesf assigned to the assignee of this application. Therefore, these features are not claimed broadly and alone herein.

lVhat is claimed is:

1. An electron discharge device comprising a vessel having a reentrant tubular stem, a metallic standard having a portion engaging said stein at a point intermediate the length of the stem, a plurality of electrodes carried by said stem, and an anode arranged within said electrodes.

2. An electron discharge device comprising a vessel having a reentrant stem, said stem comprising a plurality of coaxial portions, a standard surrounding one of said portions, a lurality of electrodes carried by said stan ard, and an anode carried by said other portion of the stem and arranged within said other electrodes.

3. An electron discharge device comprisinga tubular portion, a tilamentary electrode, a -metallic Y supporting member for said electrode, a band for attaching said member to said portion, and an anode within said electrode.-

4. An electron"v disbharge device having an electrode support, said electrode support comprising aninwardly projecting tubular portion and an electrodesupporting portion rising from said tubular portion, said tubusaid tubular portions, .and a supportingl connection between saidgcollar and said oathode, Said anode being supported from said inner tubular portion.

6. A vacuum tube comprising an anode, a cathode, a grid, a s tem sealed into one end of said vacuum tube, said stem comprising two concentric tubular portions of different diameters projecting inwardly into said tube, a collar on the outer one of said tubular portions, supporting connections from said 'collar to said cathode and said grid, lead-in wires for said cathode and said grid at one end of said tube, and an external connection from said anode leading from the other end of said tube, said anode. being supported from lsaid inner tubular portion.

i 7.A vacuum tube comprising an anode, a cathode, a stem sealed `lntoI one end of tubular portions projecting inwardly into said'tube, one of said portions encircling theother, a collar on the outer one of said tubular portions, and a supporting connection between said collar and said cathode, said anode being tubular and being mounted on said inner tubular portion and constituting a l{lire-entrant part of the envelope of said tu e. v

8. An electron discharge device, comprisingan enclosing vessel, an inwardly ro- ]ecting stem, a tubular member Vexten ing through said stem, a substantially cylindric al cathode supported from said stem, and a cup-shaped anode withinsaid cathode, said 'anode having its brim sealed in the end of said tubular member whereby a cooling fluid may be supplied to the interior ofl said anode. p Inwitness whereof, I hereunto subscribe my name this 1st day of October D., 1920.-

, VTHOMAS, R. GRIFFITH.

L said vacuum tube, saidI stem comprising two f 

